1. Field of the Invention
This invention relates to geometrical instruments and probe support devices. More particularly, the present invention relates to positioners or holders that are designed to position a small-working-volume instrument, held at the positioner's distal end, at a precise location in a larger work space. One embodiment of the present invention relates to a passive positioning arm that can hold a medical robot or instrument in a medical imagining environment.
2. Description of Prior Art
Many, modern, high precision devices (e.g., medical robots, instruments and tools) have relatively small work volumes or workspaces. A large, work-volume positioner capable of precisely positioning such devices at any location within a specified workspace is needed for the practical implementation of such small-workspace devices.
There exist many commercially available positioners and workpiece holders for these purposes. These positioners usually consist of a number of legs which are held together by various kinds of independently locking connectors and joints. See FIGS. 1A and 1B.
However, these positioners generally do not provide great flexibility in how a workpiece can be moved as it is being positioned from one point to another in a workspace of interest. One apparent solution to this problem would appear to be to add more legs and joints to such existing positioners. However, this solution can quickly become unworkable as the task of independently locking all of the additional joints of such a device becomes exceedingly cumbersome.
This need for positioners which can provide more flexibility in relocating a workpiece or instrument within a larger workspace is especially notable in the field of medicine where such small-workspace devices are constantly being put to use in an ever increasing number of medical procedures. However, a barrier can often exist to the use of commercially available positioners in many of these new medical procedures.
This situation exists because new medical procedures can utilize various real-time, noninvasive, diagnostic imaging techniques to guide the medical practitioner in the performance of the procedure. Thus, for such procedures the environment in which a medical device positioner must operate is a medical imaging environment. Such environments can place exacting requirements on the materials from which medical devices and their positioners may be made.
For example, MRI scanners utilize a strong electromagnet that generates a magnetic field that causes the electrons in a patient's body to spin in a uniform and predictable manner. The diagnostic components of such MRI equipment then manipulates the spinning electrons and uses the resulting information to generate an image of the inside of a patient's body.
However, difficulties are encountered in obtaining accurate images when disruptions and deflections in the scanner's magnetic field are experienced due to the presence in the field of materials (e.g., metals) that produce a magnetic field and/or are susceptible to producing their own magnetic fields when placed within an external magnetic field.
Thus, despite much prior art in the field of positioners and workpiece holders, there still exists a need for further improvements to such devices.
3. Objects and Advantages
There has been summarized above, rather broadly, the background that is related to the present invention in order that the context of the present invention may be better understood and appreciated. In this regard, it is instructive to also consider the objects and advantages of the present invention.
It is an object of the present invention to provide a positioning device that provides greater flexibility in how a workpiece is moved as it is being positioned from one position to another in a workspace of interest.
It is another object of the present invention to provide a positioning device that provides an easier and more convenient means for locking the various elements or legs of such a device into a desired orientation.
It is yet another object of the present invention to provide a positioning device that is compatible with use in a medical imaging environment.
It is still another object of the present invention to provide a positioning arm that can be utilized in a to-be-developed medical robot.
These and other objects and advantages of the present invention will become readily apparent as the invention is better understood by reference to the accompanying summary, drawings and the detailed description that follows.